pNFS/flexfiles: don't attempt pnfs on fatal DS errors

When an applications get killed (SIGTERM/SIGINT) while pNFS client performs a connection
to DS, client ends in an infinite loop of connect-disconnect. This
source of the issue, it that flexfilelayoutdev#nfs4_ff_layout_prepare_ds gets an error
on nfs4_pnfs_ds_connect with status ERESTARTSYS, which is set by rpc_signal_task, but
the error is treated as transient, thus retried.

The issue is reproducible with Ctrl+C the following script(there should be ~1000 files in
a directory, client should must not have any connections to DSes):

```
echo 3 > /proc/sys/vm/drop_caches

for i in *
do
   head -1 $i
done
```

The change aims to propagate the nfs4_ff_layout_prepare_ds error state
to the caller that can decide whatever this is a retryable error or not.

Signed-off-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>
Link: https://lore.kernel.org/r/20250627071751.189663-1-tigran.mkrtchyan@desy.de
Fixes: 260f32adb88d ("pNFS/flexfiles: Check the result of nfs4_pnfs_ds_connect")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

diff --git a/fs/nfs/flexfilelayout/flexfilelayout.c b/fs/nfs/flexfilelayout/flexfilelayout.c
index 4bea008dbebd7ce53aaf836b92ba638029732a29..8dc921d835388e755e18aeb338663d92311ca894 100644 (file)
--- a/fs/nfs/flexfilelayout/flexfilelayout.c
+++ b/fs/nfs/flexfilelayout/flexfilelayout.c
@@ -762,14 +762,14 @@ ff_layout_choose_ds_for_read(struct pnfs_layout_segment *lseg,
 {
        struct nfs4_ff_layout_segment *fls = FF_LAYOUT_LSEG(lseg);
        struct nfs4_ff_layout_mirror *mirror;
-       struct nfs4_pnfs_ds *ds;
+       struct nfs4_pnfs_ds *ds = ERR_PTR(-EAGAIN);
        u32 idx;
 
        /* mirrors are initially sorted by efficiency */
        for (idx = start_idx; idx < fls->mirror_array_cnt; idx++) {
                mirror = FF_LAYOUT_COMP(lseg, idx);
                ds = nfs4_ff_layout_prepare_ds(lseg, mirror, false);
-               if (!ds)
+               if (IS_ERR(ds))
                        continue;
 
                if (check_device &&
@@ -777,10 +777,10 @@ ff_layout_choose_ds_for_read(struct pnfs_layout_segment *lseg,
                        continue;
 
                *best_idx = idx;
-               return ds;
+               break;
        }
 
-       return NULL;
+       return ds;
 }
 
 static struct nfs4_pnfs_ds *
@@ -942,7 +942,7 @@ retry:
        for (i = 0; i < pgio->pg_mirror_count; i++) {
                mirror = FF_LAYOUT_COMP(pgio->pg_lseg, i);
                ds = nfs4_ff_layout_prepare_ds(pgio->pg_lseg, mirror, true);
-               if (!ds) {
+               if (IS_ERR(ds)) {
                        if (!ff_layout_no_fallback_to_mds(pgio->pg_lseg))
                                goto out_mds;
                        pnfs_generic_pg_cleanup(pgio);
@@ -1867,6 +1867,7 @@ ff_layout_read_pagelist(struct nfs_pgio_header *hdr)
        u32 idx = hdr->pgio_mirror_idx;
        int vers;
        struct nfs_fh *fh;
+       bool ds_fatal_error = false;
 
        dprintk("--> %s ino %lu pgbase %u req %zu@%llu\n",
                __func__, hdr->inode->i_ino,
@@ -1874,8 +1875,10 @@ ff_layout_read_pagelist(struct nfs_pgio_header *hdr)
 
        mirror = FF_LAYOUT_COMP(lseg, idx);
        ds = nfs4_ff_layout_prepare_ds(lseg, mirror, false);
-       if (!ds)
+       if (IS_ERR(ds)) {
+               ds_fatal_error = nfs_error_is_fatal(PTR_ERR(ds));
                goto out_failed;
+       }
 
        ds_clnt = nfs4_ff_find_or_create_ds_client(mirror, ds->ds_clp,
                                                   hdr->inode);
@@ -1923,7 +1926,7 @@ ff_layout_read_pagelist(struct nfs_pgio_header *hdr)
        return PNFS_ATTEMPTED;
 
 out_failed:
-       if (ff_layout_avoid_mds_available_ds(lseg))
+       if (ff_layout_avoid_mds_available_ds(lseg) && !ds_fatal_error)
                return PNFS_TRY_AGAIN;
        trace_pnfs_mds_fallback_read_pagelist(hdr->inode,
                        hdr->args.offset, hdr->args.count,
@@ -1945,11 +1948,14 @@ ff_layout_write_pagelist(struct nfs_pgio_header *hdr, int sync)
        int vers;
        struct nfs_fh *fh;
        u32 idx = hdr->pgio_mirror_idx;
+       bool ds_fatal_error = false;
 
        mirror = FF_LAYOUT_COMP(lseg, idx);
        ds = nfs4_ff_layout_prepare_ds(lseg, mirror, true);
-       if (!ds)
+       if (IS_ERR(ds)) {
+               ds_fatal_error = nfs_error_is_fatal(PTR_ERR(ds));
                goto out_failed;
+       }
 
        ds_clnt = nfs4_ff_find_or_create_ds_client(mirror, ds->ds_clp,
                                                   hdr->inode);
@@ -2000,7 +2006,7 @@ ff_layout_write_pagelist(struct nfs_pgio_header *hdr, int sync)
        return PNFS_ATTEMPTED;
 
 out_failed:
-       if (ff_layout_avoid_mds_available_ds(lseg))
+       if (ff_layout_avoid_mds_available_ds(lseg) && !ds_fatal_error)
                return PNFS_TRY_AGAIN;
        trace_pnfs_mds_fallback_write_pagelist(hdr->inode,
                        hdr->args.offset, hdr->args.count,
@@ -2043,7 +2049,7 @@ static int ff_layout_initiate_commit(struct nfs_commit_data *data, int how)
        idx = calc_ds_index_from_commit(lseg, data->ds_commit_index);
        mirror = FF_LAYOUT_COMP(lseg, idx);
        ds = nfs4_ff_layout_prepare_ds(lseg, mirror, true);
-       if (!ds)
+       if (IS_ERR(ds))
                goto out_err;
 
        ds_clnt = nfs4_ff_find_or_create_ds_client(mirror, ds->ds_clp,

diff --git a/fs/nfs/flexfilelayout/flexfilelayoutdev.c b/fs/nfs/flexfilelayout/flexfilelayoutdev.c
index 656d5c50bbce1cc0f4f6cd1dcb934a1c0433e640..30365ec782bb1b42823ce462179cd2d3bdcdc796 100644 (file)
--- a/fs/nfs/flexfilelayout/flexfilelayoutdev.c
+++ b/fs/nfs/flexfilelayout/flexfilelayoutdev.c
@@ -370,11 +370,11 @@ nfs4_ff_layout_prepare_ds(struct pnfs_layout_segment *lseg,
                          struct nfs4_ff_layout_mirror *mirror,
                          bool fail_return)
 {
-       struct nfs4_pnfs_ds *ds = NULL;
+       struct nfs4_pnfs_ds *ds;
        struct inode *ino = lseg->pls_layout->plh_inode;
        struct nfs_server *s = NFS_SERVER(ino);
        unsigned int max_payload;
-       int status;
+       int status = -EAGAIN;
 
        if (!ff_layout_init_mirror_ds(lseg->pls_layout, mirror))
                goto noconnect;
@@ -418,7 +418,7 @@ noconnect:
        ff_layout_send_layouterror(lseg);
        if (fail_return || !ff_layout_has_available_ds(lseg))
                pnfs_error_mark_layout_for_return(ino, lseg);
-       ds = NULL;
+       ds = ERR_PTR(status);
 out:
        return ds;
 }